1. Field of the Invention
The present invention relates to a paper feed cassette, and more particularly, it relates to a paper feed cassette mounted on an image generating apparatus.
2. Description of the Background Art
A paper feed cassette mounted on an image generating apparatus is known in general.
Japanese Patent Laying-Open No. 5-24664 (1993) discloses a paper feed cassette in which an envelope (paper) is placed on a convexly curved bottom plate (first push up member) and the envelop placed on the bottom plate is pressed by two pressure rollers mounted on forward ends of two plate springs mounted on a cassette top cover (lid member), for example. In the paper feed cassette, the envelope is lifted up by the convexly curved bottom plate and the lifted envelope comes into contact with a pick-up roller (paper feed roller). In the paper feed cassette, the two pressure rollers mounted on the two plate springs press a rear portion in a paper feed direction of the envelope against the convexly curved bottom plate, whereby the envelope is convexly curved along a convexly curved portion of the bottom plate. Thus, the envelope linearly extends along a direction (direction substantially perpendicular to the paper feed direction) in which the convexly curved portion extends, whereby warpage in the direction substantially perpendicular to the paper feed direction is inhibited from occurring in the envelope.
Japanese Patent Laying-Open No. 2001-213528 discloses a paper feed cassette in which a sheet material (paper) is lifted up by a lifter plate (first lift member) and the lifted sheet material comes into contact with a pick-up roller (paper feed roller).
Japanese Patent Laying-Open No. 8-244996 (1996) discloses a structure of a paper feed board in which a sheet (paper) is lifted up by a pressure plate and the lifted sheet comes into contact with a paper feed roller.
In the paper feed cassette disclosed in Japanese Patent Laying-Open No. 5-24664, however, the two plate springs mounted on the cassette top cover and the two pressure rollers mounted on the two plate springs must be provided in order to convexly curve the envelope (paper), whereby the number of components is disadvantageously increased. Additionally, the envelope (paper) is placed on the convexly curved bottom plate also in nonprinding, whereby the envelope (paper) is disadvantageously plastically deformed into a curved shape.
In the structures of the paper feed cassette disclosed in Japanese Patent Laying-Open No. 2001-213528 and the paper feed board disclosed in Japanese Patent Laying-Open No. 8-244996, no structure inhibiting the warpage in the direction substantially perpendicular to the paper feed direction from occurring in the sheet material and the sheet is conceivably disclosed nor suggested dissimilarly to the paper feed cassette disclosed in Japanese Patent Laying-Open No. 2001-213528.